This invention relates in general to packaging and more particularly to a container for foods and other consumable products which is constructed in a manner to provide visual evidence that the container has been opened.
The containers for cottage cheese, sour cream, yogurt, ice cream, and other food products are normally relatively inexpensive "tub" type containers that are typically formed from coated paperboard or injection molded, or thermoformed thermoplastic materials such as polyethylene or polystyrene. The container is provided with a lid which must fit tightly on the container in order to give the product a prolonged shelf life. The periphery of the lid and the rim of the container are usually formed to mechanically interlock with one another in order to hold the lid in place and at the same time effectively seal the container contents. The lid can be removed to provide access to the container contents and can be replaced by pressing it back onto the container to again seal the contents.
One problem with conventional food containers of this type is that the lid can be removed and the contents can be tampered with while the package is on a store shelf or elsewhere. After the lid has been replaced, there is no visible indication given that tampering has occurred, and potential purchasers have no way of knowing that tampering may have taken place.
In the past, there have been well publicized incidents involving the intentional adulteration of consumable products with poisons and other harmful substances. These incidents and the possibility of other types of tampering have caused the packaging industry to make efforts at providing containers which are either tamper proof or tamper evident. Although tamper evident containers can be opened when still on the shelf in a store, the fact that they have been opened is evidenced by an easily visible indication alerting the public to the fact that tampering has taken place and the contents may be contaminated. Examples of tamper evident containers are found in U.S. Pat. Nos. 4,190,175 to Allen, 4,146,148 to Dwinell et al., 4,488,658 to Smith et al., and 4,493,432 to Smith.
All of the known food packages of this type require that an actual part of the lid itself be torn or broken away before the container can be opened. Consequently, the lids must be specially constructed in order to provide them with the special tear away sections. This requires special manufacturing operations for forming the lids, along with all of the other problems and costs associated with designing, developing and manufacturing a completely new lid construction.